This video was filmed on the backside of Mt Clocher in the French Alps. The wind was around 10-12mph, off-center to the right about 25-30 degrees. The slope itself is not very steep, meaning the lift generated was adequate but far from exceptional. Thermals were coming through fairly frequently, and when they did, the direction of the incoming wind would shift dramatically, often killing the slope lift almost entirely as they’d blow through. Overall, the conditions were fun, but challenging in a way that coastal sites with steady onshore seabreezes aren’t.
This is a pretty typical situation at a lot of inland and mountain slopes, and trying to link low level VTPR aerobatic figures in such conditions can be tricky. Glider aerobatics is always about careful and subtle energy management, but when the lift itself is varying so frequently, deft handling of one’s energy becomes even more important.
I shared this video for the specific reason that I wanted to demonstrate some techniques and tactics I use to keep the aerobatic flow going even in situations where the lift isn’t great:
– I primarily focus on establishing vertical uplines aka “half piping” immediately, as these are the “engine” that keeps your airspeed / energy going. You can see I do this right on launch. By using the punchier vertical lift on the right hand side to gain back altitude / speed / energy, I was able to mostly keep a steady flow of figures going – at least until a thermal would blow through.
– You can also do a form of frontside dynamic soaring, where you do vertical loops in the middle of the “aerobatic box” (i.e right in front of you), exploiting the punchier side of the slope to keep and (hopefully) generate speed.
– On shallow slopes like these, I use the depth of the slope to my advantage when the wind shifts / a thermal blows through / I’ve done some “expensive” (in terms of energy) figures like low-level snaprolls, etc. When the wind is good, I try to stay as close to myself / high on the hill as possible, but as the lift starts to peter out, I trade altitude for airspeed by moving down / away on the slope. This lets me keep my halfpipes going for a bit longer before I’m forced to go thermal hunting. Sometimes the lift will pick back up and you don’t have to, you just work some in/out figures into your sequence and bring it back up high.
– Eventually you have to go thermal hunting. I am far from a slope / thermal expert, but generally speaking I can find and exploit thermals reasonably well in a slope setting. Anyways, this is an essential skill for mountain / inland flying. Find a thermal, climb out, and eventually, dive, using the speed to perform some high-speed acro, and finishing in a way that (hopefully) lets you re-establish your energy-sustaining halfpipes.
Hope it’s interesting or at least a little helpful 🙂